| 摘要 |
There is provided a bone screw known per se, having a threaded portion (2) and a reception part (5) for receiving a rod (29) to be connected to the bone screw. The securing and locking action of the connection between the bone screw and the rod is provided by an exterior nut (13). To provide for the required strength and durability of the connection, the exterior nut (13) comprises an inside sleeve-shaped element (17) having a predetermined inner dimension and an outer diameter which is almost equal to or slightly less than the diameter of the bore (8), and a pressure element (22) arranged therein. The pressure element (22) comprises a first section (26) at its end facing the bottom of the bore hole (8). The outer dimension of the first section is greater than the predetermined inner dimension and the first section causes the element (17) to be expanded when pressure is exerted on the rod (29) to be received.
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